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Let's talk! - Nutrition and ... Calories

I am SO excited to start a collection of posts called “Lets Talk! Nutrition and _______”! I have been thinking about this idea for a long time, inspired to provide reliable and accessible information on the science of nutrition to equip people to critically think through what they read and hear about food. Here and in future “Let’s Talk” posts, you can expect several truths that are often overlooked.

What better place to start than Calories! Yes, the “c” is capitalized; the full term for Calories with respect to food is kilocalories, which is just a mouthful to say! Calories are counted, feared, cut, bashed, and used as the basis for food choices, but would this be different if you knew what a Calorie actually is? The term Calorie originates from the early 1800’s in France and was used to measure heat in chemistry, physics, and engineering, with its first appearance in medical text books in 1894¹ – fascinating! What this means is that a Calorie is NOT something physical, but rather the measurement of the energy food can provide¹, known as potential energy. What? You mean I am not eating physical Calories!? Well, this depends how abstract you want to get….but the answer is no, you do not eat physical Calories.

Enter metabolism. Potential energy in the context of food is chemical potential energy. Simply put, the energy released through the process of breaking and reforming chemical bonds in food (a.k.a metabolism) is measured in Calories ². Abstract, but true! You can use the analogy of fuel for your car: the food you eat is the gasoline, the Calories is the amount of energy released when the fuel combusts to run the engine (your body).

So the elephant in the room, do Calories matter? My first answer - ABSOLUTELY! In fact, they matter a great deal since every single cell in your body needs energy to function, therefore your survival depends on your bodies ability to release energy from food. My second answer and more importantly - Calories matter, but not as much as the food they come from ³. For example, if I want a 100 Calorie snack, I can choose to eat a 100 Calorie snack pack of mini cookies OR I can choose to eat 1 medium-sized piece of fruit. The cookies are called "energy-dense", meaning that they do not provide many vitamins and minerals for the amount of Calories they provide. The fruit is called "nutrient-dense", meaning that it provides a lot of vitamins and minerals for the amount of Calories. Choosing nutrient-dense foods frequently and saving energy-dense foods for treats improves the overall quality of your diet and can help promote good health ³.

Nutrient Dense Foods Energy Dense Foods

The total number of Calories you eat counts for your health in a general sense based on the Law of Conservation of Energy: energy can neither be created nor destroyed. If the energy provided by the food you eat does not get used by your body, it doesn't just disappear but rather our efficient and survival-oriented bodies store it for future. This storage is beneficial when food is scarce but leads to weight gain when food is abundant. However determining the exact number of Calories each person needs is complex since it depends on factors beyond basic things such as height, weight, age, and physical activity. Instead of focusing on exact numbers of Calories, try to gain an understanding of the general amount of nutrient-dense food your body needs each day to fuel your life.

Check out this very user-friendly TED talk that provides an excellent explanation of Calories⁴.

I would like to close by making a bold statement. There are no good or bad Calories. If this shocks you, go back to the top of this post. There cannot be good or bad Calories because Calories are simply a way to measure energy. BUT, the food that Calories come from are not created equal; they have different metabolic effects on our body and can impact health in different ways³. I challenge you to reframe your language. Move away from "good" and "bad”. Rather than counting Calories, focus on fuelling our body with quality foods that will provide energy and other nutrients essential for life³.


1. Hargrove, J.L. (2006). History of the Calorie in nutrition. The Journal of Nutrition, 136(12), 2957-2961. 2. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell, 4th edition. New York: Garland Science. 3. Lucan, S.C., & DiNicolantonio, J.J. (2014). How calorie-focused thinking about obesity and related diseases may mislead and harm public health. An alternative. Public Health Nutrition, 18(4), 571-581. 4. Bryce, E. (n.d.). Ted Ed: What is a Calorie? Retrieved from:


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